1. Field of the Invention
This invention relates to a metallic golf club head and, more particularly, to a metallic golf club head having a hollow head body and a sole member with a weight, and further relates to a method of manufacturing the same.
2. Description of the Related Art
Recently, a metallic golf club head made of titanium or titanium alloy (hereinafter referred to as "titanium") has become popular because of the following reasons: (a) titanium is high in restitution; (b) titanium is light in weight, though not as light as carbon, small in specific gravity, and high in rigidity (therefore, a golf club head made of titanium can be formed to have a large hollow head body); and (c) a weight can thus be disposed in any portion of the hollow head body to adjust the center of gravity.
However, titanium is hard to weld to a metal other than titanium. Therefore, a face member or a sole member made of a metal other than titanium can not be welded to a hollow head body made of titanium, or a weight made of a metal other than titanium can not be welded to a face member or a sole member made of titanium.
Generally, the following method of fixing a weight in a golf club head body has been adopted. As shown in FIG. 9, a plurality of holes are formed in a sole member 52, which will be welded to a hollow head body 51. A hole is formed in each weight 53. Each weight 53 is arranged on the inner surface of the sole member 52 so as to align the hole of the sole member 52 with that of the weight 53. A rivet 54 is inserted into the hole of the sole member 52 and that of the weight 53 from the sole member side. Then, the tip end of the rivet 54 is caulked so as to fix the weight 53 to the sole member 52. Finally, the sole member 52 with the weight 53 is welded to the head body 51.
Furthermore, Japanese Laid-open (unexamined) Patent Application No. H6-296716 discloses another method of fixing a weight in a golf club head body. According to this method, a hole is formed in a sole member as well as in a weight. The weight is arranged on the inner surface of the sole member. A bolt is inserted into the holes of the sole member and the weight from the sole member side. Then, the bolt is tightened by a nut so as to fix the weight to the sole member.
In both of the above-mentioned methods, rivets or bolts are used to fix a weight to a sole member. Accordingly, in addition to a process for forming a head body and a sole member, a process for boring a hole for inserting the rivet or the bolt in a weight and a sole member is required. Moreover, a plurality of processes for tightening bolts or caulking rivets are required. Therefore, it takes time for manufacturing a golf club head having a weight.
In a golf club head in which bolts and nuts are used for securing a weight, nuts may loosen with time, resulting in a wobbling weight.